Example:

Note

Digest authentication provides a more secure password system
than Basic authentication, but only works with supporting
browsers. As of November 2002, the major browsers that support digest
authentication are Opera, MS Internet
Explorer (fails when used with a query string - see "Working with MS Internet Explorer" below for a workaround), Amaya, Mozilla and Netscape since version 7. Since digest authentication is not
as widely implemented as basic authentication, you should use it only
in controlled environments.

The Digest authentication implementation in current Internet
Explorer implementations has known issues, namely that GET
requests with a query string are not RFC compliant. There are a
few ways to work around this issue.

The first way is to use POST requests instead of
GET requests to pass data to your program. This method
is the simplest approach if your application can work with this
limitation.

Since version 2.0.51 Apache also provides a workaround in the
AuthDigestEnableQueryStringHack environment variable.
If AuthDigestEnableQueryStringHack is set for the
request, Apache will take steps to work around the MSIE bug and
remove the request URI from the digest comparison. Using this
method would look similar to the following.

Using Digest Authentication with MSIE:

BrowserMatch "MSIE" AuthDigestEnableQueryStringHack=On

See the BrowserMatch
directive for more details on conditionally setting environment
variables

The AuthDigestDomain directive allows
you to specify one or more URIs which are in the same protection
space (i.e. use the same realm and username/password info).
The specified URIs are prefixes, i.e. the client will assume
that all URIs "below" these are also protected by the same
username/password. The URIs may be either absolute URIs (i.e.
including a scheme, host, port, etc) or relative URIs.

This directive should always be specified and
contain at least the (set of) root URI(s) for this space.
Omitting to do so will cause the client to send the
Authorization header for every request sent to this
server. Apart from increasing the size of the request, it may
also have a detrimental effect on performance if AuthDigestNcCheck is on.

The URIs specified can also point to different servers, in
which case clients (which understand this) will then share
username/password info across multiple servers without
prompting the user each time.

The AuthDigestNonceLifetime directive
controls how long the server nonce is valid. When the client
contacts the server using an expired nonce the server will send
back a 401 with stale=true. If seconds is
greater than 0 then it specifies the amount of time for which the
nonce is valid; this should probably never be set to less than 10
seconds. If seconds is less than 0 then the nonce never
expires.

The AuthDigestQop directive determines
the quality-of-protection to use. auth will only do
authentication (username/password); auth-int is
authentication plus integrity checking (an MD5 hash of the entity
is also computed and checked); none will cause the module
to use the old RFC-2069 digest algorithm (which does not include
integrity checking). Both auth and auth-int may
be specified, in which the case the browser will choose which of
these to use. none should only be used if the browser for
some reason does not like the challenge it receives otherwise.

The AuthDigestShmemSize directive defines
the amount of shared memory, that will be allocated at the server
startup for keeping track of clients. Note that the shared memory
segment cannot be set less than the space that is neccessary for
tracking at least one client. This value is dependant on your
system. If you want to find out the exact value, you may simply
set AuthDigestShmemSize to the value of
0 and read the error message after trying to start the
server.

The size is normally expressed in Bytes, but you
may let the number follow a K or an M to
express your value as KBytes or MBytes. For example, the following
directives are all equivalent: